<template>
<div class="home-page">

  <div class="banner">
    <div class="container">
      <h1 class="logo-font">conduit</h1>
      <p>A place to share your knowledge.</p>
    </div>
  </div>

  <div class="container page">
    <div class="row">

      <div class="col-md-9">
        <div class="feed-toggle">
          <ul class="nav nav-pills outline-active">
            <li v-if="user" class="nav-item">
              <nuxt-link class="nav-link"
              :class="{
                active: tab === 'your_feed'
              }"
              exact
              :to="{
                name: 'home',
                query: {
                  tab: 'your_feed'
                }
              }"
              >Your Feed</nuxt-link>
            </li>
            <li class="nav-item">
              <nuxt-link class="nav-link"
              :class="{
                active: tab === 'global_feed'
              }"
              exact
              :to="{
                name: 'home',
                query: {
                  tab: 'global_feed'
                }
              }"
              >Global Feed</nuxt-link>
            </li>
            <li v-if="tag" class="nav-item">
              <nuxt-link class="nav-link"
              :class="{
                active: tab === 'global_feed'
              }"
              exact
              :to="{
                name: 'home',
                query: {
                  tab: 'tag',
                  tag: tag
                }
              }"
              ># {{ tag }}</nuxt-link>
            </li>
          </ul>
        </div>

        <div class="article-preview" v-for="article in articles" :key="article.slug">
          <div class="article-meta">
            <nuxt-link :to="{
              name: 'profile',
              params: {
                username: article.author.username
              }
              }">
              <img :src="article.author.image" />
            </nuxt-link>
            <div class="info">
              <nuxt-link class="author" :to="{
                name: 'profile',
                params: {
                  username: article.author.username
                }
              }">
              {{ article.author.username }}
              </nuxt-link>
              <span class="date">{{article.createAt | date}}</span>
            </div>
            <button  @click="onFavorite(article)" :disabled="article.favoriteDisabled" class="btn btn-outline-primary btn-sm pull-xs-right" :class="{active: article.favorited }">
              <i class="ion-heart"></i> {{article.favoritesCount}}
            </button>
          </div>
          <nuxt-link :to="{
            name: 'article',
            params: {
              slug: article.slug
            }
          }" class="preview-link">
            <h1>{{ article.title }}</h1>
            <p>{{ article.description }}</p>
            <span>Read more...</span>
          </nuxt-link>
        </div>
        <!-- 分页列表 -->
        <nav>
          <ul class="pagination">
            <li class="page-item" v-for="item in totalPage" :class="{
              active: item === page
            }" :key="item">
              <nuxt-link class="page-link" :to="{
                name: 'home',
                query: {
                  page: item,
                  tag: $route.query.tag,
                  tab: tab
                }
              }">{{ item }}</nuxt-link>
            </li>
          </ul>
        </nav>
        
      </div>

      <div class="col-md-3">
        <div class="sidebar">
          <p>Popular Tags</p>

          <div class="tag-list">
            <nuxt-link :to="{
              name: 'home',
              query: {
                tab: 'tag',
                tag: item
              }
            }" class="tag-pill tag-default" v-for="item in tags" :key="item">{{item}}</nuxt-link>
          </div>
        </div>
      </div>

    </div>
  </div>

</div>
</template>

<script>
import  { 
  getArticles,
  getYourFeedArticles,
  addFavorite,
  deleteFavorite
} from '@/api/article'
import { getTags } from '@/api/tag'
import { mapState } from 'vuex'
export default {
  name: 'HomePage',
  async asyncData ({ query }) {
    const page = Number.parseInt(query.page || 1)
    const limit = 20
    const tab = query.tab || 'global_feed'
    const tag = query.tag
    const loadArticles = tab !== 'your_feed'
    ? getArticles
    : getYourFeedArticles
    const [ articleRes, tagRes ] = await Promise.all([
      loadArticles({
        limit,
        offset: (page - 1) * limit,
        tag
      }),
      getTags()
    ])
    const { articles, articlesCount } = articleRes.data
    const { tags } = tagRes.data
    articles.forEach(article => article.favoriteDisabled = false)
    return {
      articles,
      articlesCount, // 文章列表
      tags, // 标签列表
      limit, // 每页大小
      page, // 页码
      tab, // 选项卡
      tag // 数据标签
    }
  },
  watchQuery: ['page', 'tag', 'tab'],
  computed: {
    ...mapState(['user']),
    totalPage () {
      return Math.ceil(this.articlesCount / this.limit)
    }
  },
  methods: {
    async onFavorite (article) {
      if (!this.user ) return this.$router.push('/login')
      article.favoriteDisabled = true
      if (article.favorited) {
        // 取消点赞
        await deleteFavorite(article.slug)
        article.favorited = false
        article.favoritesCount -= 1
      } else {
        // 点赞
        await addFavorite(article.slug)
        article.favorited = true
        article.favoritesCount += 1
      }
      article.favoriteDisabled = false
    }
  }
}
</script>